The National had a production of An Inspector Calls that was touring recently - not sure if it still is?

It's worth looking at productions that have been released on DVD as well. You'll certainly get a Globe and an RSC Macbeth. It's not as good as seeing it live, but the cinematography is so good that you lose less than I thought you would and you really get a sense of the staging.

I've always wondered why local theatres don't schedule GCSE texts each year. It seems to me that there would be a good market for school trips and you could use it as an opportunity for recent drama students so could presumably run it at equity minimum fees.

Your son's school will be able to access National Theatre on demand for free to show both versions of Danny Boyle's Frankenstein (Jonny Lee Miller and Benedict Cumberbatch switch roles between the monster and Dr F). There are also lots of supporting video resources on this site.

Rory Kinnear comes to the National Theatre in Spring 2018 in Macbeth, which will be broadcast live at some point during the run.

The David Thewlis one (Inspector Calls) is quite a bit different from the text, it has flashbacks and recreations, but it is very good. Available from ebay etc on dvd. DD said she thought it helped her to understand the play as a whole and the characters.

It's on at some small London venues. It interweaves the story of the book with the story of Mary Shelley herself. Very cleverly adapted and yes, it is very different from the book, but very true to the spirit of it. I think a different adaptation provides a lot of food for thought for students and this one also really useful for context and background of when it was written. Can't recommend highly enough.

Also agree the NT one is good and your son's school can access for free.